A sexual encounter that is over the top and extremely memorable for any number of reasons.

Duder 1: "Yo dude did you see the girl I went home with last night?"

Duder 2: "Yeah boi! She was so hot."

Duder 1: "Well anyway, I get to her place and we start making out. Then, her roommate comes home, who is f*cking smoking hot by the way, and she joins in! I railed both those sweet asses for like 3 hours!"

Duder 2: "Holy shit! That's one epic fuck doggy! I bet that'll be #1 in your spank bank for a long time."